1. Field of the Invention
This invention relates to a connector housing in which an elastic seal ring for maintaining watertightness with a counter connector housing is disposed inside a hood portion used for engagement with the counter connector housing.
2. Background
A method of producing a conventional connector housing of this type is described in Japanese patent publication No. Hei. 3-219578.
FIG. 7A shows a housing A which is produced by the above-mentioned method. The housing A comprises a hood portion 3 and an elastic seal ring 4. The hood portion 3 is expandedly formed via a step 2.sub.1 of a housing body portion 1 so as to receive a counter connector housing. The elastic seal ring 4 is integrally disposed in a basal end portion of the hood portion 3, i.e., between the first step 2.sub.1 and a second step 2.sub.2. The elastic seal ring 4 comprises retaining pieces 4a. The retaining pieces 4a are respectively engaged in a tight manner with through holes 3a which are formed in the hood 3 in a direction perpendicular to a fitting axis of the housing. In the figure, 1a designates terminal accommodating chambers disposed inside the housing body 1.
The waterproof connector housing A is produced in the following manner, according to the publication. The housing body portion 1 and the hood portion 3 are molded in a primary molding step, and the elastic seal ring 4 is formed in a secondary molding step. In the primary molding step, upper and lower molds which are not shown are clamped together in an axial direction of the housing A to be molded, so that the connector housing is formed by injection molding in accordance with a conventional method. In this molding process, a slide mold which slides in a direction perpendicular to the axial direction is disposed between the upper and lower molds. Passageways 3a are formed for introducing an elastic material from the slide mold to a portion in which the seal ring is to be formed inside the hood portion 3. The passageways 3a function also as engagement holes for the retaining pieces 4a.
FIG. 7B shows the state of the secondary molding. An upper mold 6' having a vacant space 8 corresponding to the portion in which the elastic seal ring is to be formed, and the lower mold 5 which holds the housing body portion 1 are clamped together. Then, a liquid elastic material is introduced into the portion (the vacant space 8) in which the seal ring is to be formed, from a gate 9a of a runner 9 disposed in the slide mold 7 via the passageways 3a of the hood portion 3.
In the primary molding step, ridges (not shown) protruding in the axial direction are formed at the first and second steps 2.sub.1 and 2.sub.2 in the housing A. Similar ridges are formed over a total length of the outer periphery of each passageway 3a. These ridges are pressed and crushed when the upper mold 6' abuts against the slide mold 7 during the clamping, so that these molds come in tight contact with each other. As a result, it is possible to prevent the liquid elastic material having good fluidity from leaking.
FIG. 8 is a section view taken along a plane which is perpendicular to the axial direction of the housing A and includes the passageways 3a (the terminal accommodating chambers are not illustrated). The housing body 1 is engaged with the seal ring 4 made of the elastic material by only the retaining pieces 4a and the engagement holes 3a. The housing portion and the seal ring are integrally formed as described above, but the materials thereof are different from each other. When the housing is to be fitted with a counter connector housing, therefore, a portion of the seal ring 4 other than the vicinity of the engagement portion may be stripped off so as to produces problems such as the engagement operation becomes difficult to do, and that sufficient watertightness cannot be attained.
In the housing A, it may be considered that such stripping can be suppressed by increasing the number of engagement points between the retaining pieces 4a and the engagement holes 3a. Since the engagement holes 3a are formed by the slide mold as described above, however, such a countermeasure results in an increase of the production cost of molds and hence an increase of the cost of the product.
Japanese patent publication No. Hei. 3-219578 describes also a connector housing B shown in FIG. 9. The housing B comprises retaining pieces 4a' and engagement holes 3a' which are disposed in a step 2.sub.1 '. In the housing B, engagement points exist in the step 2.sub.1 '. When the housing is to be fitted with a counter connector housing, therefore, a leading portion Q of a seal ring 4' is easily stripped off. That is, the housing B involves the same problems as those of the housing A.